The present invention relates to an air-supported laying roller for textile yarns, the roller being fed from a central air supply to the central shaft and being provided with an air cushion to the roller shell via porous bearing bushings between the shaft and the shell.
A laying roller has textile yarn wound on its outer shell and the removal of the yarn spins the shell around the central support or shaft of the roller and unwinds the yarn. An air cushion supports the shell as it rotates. A number of such laying rollers have become known.
Federal Republic of Germany OS 21 34 247 discloses a laying roller in which air is supplied via the shaft, which is strengthened in the region of the roller shell. A plurality of annular rows of radial holes in the shaft cause the emergence of air to the inside diameter of the shell. For axial stabilization, holes are also provided in the ends of the shaft. These holes permit the emergence of air which presses against bucket wheel like disks which are pressed into the roller shell.
The four local air outlets at the ends of the shaft do not permit a balanced air cushion inside the shell, because the air can escape from the shaft and from inside the shell in an uncontrolled fashion. The annular rows of holes, each of a plurality of radially arranged holes, do not contribute to a balanced air cushion either. Another disadvantage is the large pressure space within which the air must be compressed. Experience has shown that a pressure drop occurs at the rear series of air outlet openings. The result of this is metallic shell to shaft contact and thus failure of the laying roller.
Federal Republic of Germany OS 20 03 345 discloses a ceramic air bearing in the form of a laying roller. In this case, an air cushion results from the relative speed of the roller shell with respect to the stationary ceramic part inside the shell. Outside air is not used here. Axial stabilization is effected via small magnet plates. The danger of contact between the ceramic part and the roller shell is present here to even a greater extent than in the previously described embodiment. In particular, contact cannot be avoided upon the starting and stopping of the roller. Failure after a short period of travel is virtually certain here.